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A protein in blood serum that is a component of the innate immune system, acting as a positive regulator of the alternative pathway of the complement system.

[Probably pro- + Latin perdere, to destroy; see perdition + -in.]


(Medicine) immunol a protein present in blood serum that, acting with complement, is involved in the destruction of alien cells, such as bacteria
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Persons with persistent complement component deficiencies (including inherited or chronic deficiencies in C3, C5-C9, properdin, factor D, factor H, or who are taking eculizumab [Solaris]); persons with anatomic or functional asplenia (including sickle cell disease); microbiologists routinely exposed to isolates of Neisseria meningitidis; persons identified as at increased risk because of a serogroup B meningococcal disease outbreak.
In the alternative complement pathway, C3b reacts with the proteins factor B, adipsin, and properdin to compose C3 convertase.
Morrison DC, Kline LF (1977) Activation of the classical and properdin pathways of complement by bacterial lipopolysaccharides (LPS).
Moreover, tubular heparan sulfate proteoglycans provide a docking platform for activation of the alternative pathway of the complement cascade via properdin, which may play a role in proteinuric renal damage [32].
The hyalinotic lesions are usually formed by nonspecific trapping of the high-molecular-weight circulating proteins, such as IgM and C1q, and these lesions must be distinguished from the immune-complex deposits seen in other forms of glomerular diseases, where additional components of the complement, that is, C3 and properdin, also display reactivity in these deposits.
TABLE Patients at high risk for meningococcal disease * Individuals with persistent complement component deficiency, such as C5-C9, properdin, or factor D * People with functional or anatomical asplenia * Microbiologists working with Neisseria meningitidis * Travelers to, or residents of, countries where meningococcal disease is hyperendemic or epidemic Source: CDC.
Kompleman sisteminin gec komponentlerinden olan C5-C9 eksikliginde meningokoklar ile rekurren menenjit gelisimi bilinirken, properdin eksikliginde meningokokkal menenjitler daha yuksek mortalite ile seyretmektedir.
Infants with complement component deficiencies such as C3, C5-9, properdin, factor H, and factor D deficiencies.
They discuss such topics as B cell signaling and fate decision; immune function control; the molecular components, geometry, and timing of T cell activation and synapse formation; the influence of bacterial carbohydrates on the adaptive immune system; new findings on properdin and the role in inflammatory and autoimmune diseases; allergy vaccines based on allergen structures; adaptive immune regulation in the gastrointestinal tract; the acute inflammatory response and sterile stimuli; the role of antibodies in HIV vaccines; and functions of notch signaling in the immune system.
18) In May 2007, NACI recommended the use of the quadrivalent meningococcal vaccine for immunization of persons 2-55 years in the following high-risk groups: persons with anatomic or functional asplenia; persons who have complement, properdin, or factor D deficiencies; travelers when meningococcal vaccine is indicated, including pilgrims to the Hajj in Mecca; research, industrial, and clinical laboratory personnel who are routinely exposed to N.
It also increases properdin levels, which accounts for its antibiotic effects.
This study indicates that a combined deficiency of both properdin and MBL increases the risk of infection with N.